The present invention relates to a method determining the processing position of a charged particle beam apparatus such as focused ion beam apparatus (FIB) and scanning electron microscope, and relates especially to a method of determining a processing position below the sample surface, which cannot be seen by a visible light optical microscope, and a laser microscope used in the method.
In a processing positioning in a conventional charged particle beam apparatus, the processing position has been determined by a superposition of a visible light optical microscope image and a secondary charged particle image by a charged particle beam irradiation (for example, refer to Patent Document 1). Or, the processing position has been determined by performing a marking by a laser optical system disposed coaxially with a visible light optical observation system in the vicinity of a processing/observation object area, and by a superimposition of the optical image in a place where the marking has been performed and the secondary charged particle image (for example, refer to Patent Document 2).
[Patent Document 1] JP-A-11-144670 (4th-5th pages, FIGS. 3-4)
[Patent Document 2] JP-A-11-329315 (4th page, FIG. 1)
In the conventional processing positioning, in a case where the processing/observation area exists below the sample surface and an upper layer is not a transparent film like an insulating film, there has been the problem that the processing area cannot be observed by a visible light optical microscope. Further, there have been the problems that, even in the case where the surface is a transparent film like the insulating film and the processing/observation object area can be observed by the visible light optical microscope, it is impossible to perform a laser marking because there exists no absorption of the laser beam in the insulating film and, in a case where no characteristic shape exists on the sample surface, the superposition cannot be performed by the secondary charged particle image and the visible light optical microscope image, by which only the sample surface can be observed.
It is the goal of the present invention to solve the above issues and thereby provide an application to provide, in a sample comprising a wiring pattern of a semiconductor sample such as an IC, a technique for a sample whose wiring pattern layer is covered by an opaque film, which does not depend on the sample surface shape, thereby accurately and easily performing the processing positioning in the charged particle beam apparatus.